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How was geological time named?

lpetrich

lpetrich

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Why do geologists use all these odd names for the past? Here is the history behind them.

It started in 1759, when Italian geologist Giovanni Arduino (1714-1795) sorted out the rocks of the Alps into four layers. Primary was the schists from the core of the mountains, secondary was the hard sedimentary rocks on the mountain flanks, tertiary was the less hardened sedimentary rocks of the foothills, and quaternary was volcanic layers.

His work was extended by later geologists, and over the first half of the nineteenth century, they marked out the major divisions in the fossil-rich parts of the geological record, and in the twentieth century, completed that work. Time intervals are marked out in a hierarchy, with smaller ones being subintervals of larger ones. From largest to smallest:
[table="class: grid"]
[tr][th]Time range[/th][th]Rocks in it[/th][/tr]
[tr][td]Eon[/td][td]Eonothem[/td][/tr]
[tr][td]Era[/td][td]Erathem[/td][/tr]
[tr][td]Period[/td][td]System[/td][/tr]
[tr][td]Epoch[/td][td]Series[/td][/tr]
[tr][td]Age[/td][td]Stage[/td][/tr]
[tr][td]Chron[/td][td]Chronozone[/td][/tr]
[/table]

The best-known eras are Paleozoic "old life", Mesozoic "middle life", Cenozoic "new life", and they were named in 1841 by English geologist John Phillips (1800-1874) They are marked out by mass extinctions, extinctions that were very obvious in marine invertebrates, the most common sort of fossil.

Turning to periods, the Cenozoic Era was for a long time divided into Tertiary and Quaternary Periods, but in 1853, Austrian paleontologist Moritz Hoernes (1815-1868) divided the Tertiary into Paleogene "old generation" and Neogene "new generation" subperiods. Nowadays, the Cenozoic is divided into Paleogene, Neogene, and Quaternary Periods.

The Mesozoic Era is divided into Triassic, Jurassic, and Cretaceous Periods, and the Paleozoic into Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods.

The Triassic was marked out in 1834 by Friedrich von Alberti, naming it from it having three distinctive rock layers in southern Germany.

The Jurassic was marked out in 1829 by the French naturalist Alexandre Brongniart (1770-1847), naming it after the Jura Mountains of the France-Switzerland border.

The Cretaceous "chalky" was marked out in 1822 by Belgian geologist Jean d'Omalius d'Halloy (1783-1875).

The Cambrian was marked out in 1835 by English geologist Adam Sedgwick (1785-1873), naming it after the Latinized version of Cymru, Welsh for Wales.

The Ordovician was marked out in 1879 by English geologist Charles Lapworth, naming it after the Ordovices, a pre-Roman tribe in north Wales. He marked it out to resolve a dispute between the followers of Adam Sedgwick and Roderick Murchison on where the Cambrian-Silurian boundary should be.

The Silurian was marked out in 1839 by English geologist Roderick Murchison (1792-1871), naming it after the Silures, a pre-Roman tribe in south Wales.

The Devonian (Devon, England) was marked out in 1840 by Adam Sedgwick and Roderick Murchison.  The Great Devonian Controversy was about where the Silurian-Carboniferous boundary should be, and like the Cambrian-Silurian one, it was resolved by creating a new geological period.

The Carboniferous "coal-bearing" was marked out in 1822 by English geologists William Phillips (1775-1828) and William Conybeare (1787-1857).

The Permian (Perm, Russia) was marked out in 1841 by Roderick Murchison.
 
The Carboniferous Period has long been divided by North American geologists into the Mississippian and Pennsylvanian periods, named after two US states. This issue has been resolved by making them subperiods of the Carboniferous.

Periods are often divided into epochs as Early / Lower and Late / Upper, or else Early / Lower, Middle, and Late / Upper. Some periods have more properly named epochs, however.

The Cenozoic Era is divided into (periods) and epochs as follows: (Tertiary, Paleogene) Paleocene, Eocene, Oligocene, (Tertiary, Neogene) Miocene, Pliocene, (Quaternary) Pleistocene, Holocene.

Paleocene "old recent" was marked out in 1874 by French geologist and paleobotanist Wilhelm Philippe Schimper (1808-1880) as a split of the Eocene.

Eocene "dawn recent" was marked out in 1833 by English geologist Charles Lyell (1797-1875).

Oligocene "a little recent" was marked out in 1854 by German paleontologist Heinrich Ernst Beyrich (1815-1896) as a split of the Eocene.

Miocene "less recent" was marked out in 1833 by Charles Lyell.

Pliocene "more recent" was marked out in 1833 by Charles Lyell.

Pleistocene "most recent" was marked out in 1839 by Charles Lyell as a split of the Pliocene.

Holocene "whole recent" was marked out in 1833 by Charles Lyell as "Recent". It was renamed in 1867 by French paleontologist Paul Gervais (1816-1879).

Here's a timeline:
  • 1833: Eocene, Miocene, Pliocene, Recent
  • 1839: Eocene, Miocene, Pliocene, Pleistocene, Recent
  • 1854: Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Recent
  • 1867: Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene
  • 1874: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene
 
Epochs, in turn, are divided into ages. Here are those in the Holocene: Greenlandian, Northgrippian, and Meghalayan.

I won't get into pre-Cenozoic epochs or pre-Holocene ages, but I wish to note that the large majority of geological-time names are region names, followed by position-in-sequence names. Feature names are rare, names like Carboniferous and Triassic and Cretaceous.

So far, I've been discussing everything after the beginning of the Fortunian Age, the Terreneuvian Epoch, the Cambrian Period, the Phanerozoic Era. But what about the rest of the Earth's history?

All the time from the Cambrian to the Holocene was named the Phanerozoic "visible life" Eon in 1930 by American geologist George Halcott Chadwick (1876-1953). All the time before it he called the Cryptozoic "hidden life" Eon. But it is more usually called the Precambrian.

The Precambrian has been divided into eons, the Proterozoic "former life", Archean "ancient", and Hadean, after the underworld of Greek mythology.

Archean was introduced as an alternate name for the entire Precambrian in 1872 American geologist James Dwight Dana (1813–1895). It was also called the Azoic "lifeless", Archeozoic "ancient life", and Eozoic "dawn life", the latter in 1865 by Canadian geologist John William Dawson (1820-1899).

I can't find out when the Proterozoic was marked out.

The Hadean was marked out in 1972 by American geologist Preston Cloud (1912-1991).

The Proterozoic Eon is divided into Paleo- "old", Meso- "middle", and Neo- "new" -proterozoic Eras.

The Archean Eon is divided into Eo- "dawn", Paleo- "old", Meso- "middle", and Neo- "new" -archean Eras.
 
The Proterozoic Eon is divided into (Paleo) Siderian "iron", Rhyacian "stream of lava", Orosirian "mountain range", Statherian "stable, firm", (Meso) Calymmian "cover", Ectasian "extension", Stenian "narrow", (Neo) Tonian "stretch", Cryogenian "cold making", Ediacaran (Ediacara Hills, Australia) Periods.

The Ediacaran attained official status in 2004, and the Cryogenian in 1990.

Most of the subdivisions of the Precambrian are defined as arbitrary times without refrerence to any geological features, but I've seen a proposed alternative:

Proposed Precambrian timeline - Geologic time scale - Wikipedia

  • Hadeon Eon: Chaotian Era, Jack Hillsian or Zirconian Era
  • Archean Eon
    • Paleo- Era: Acastan, Isuan Periods
    • Meso- Era: Vaalbaran, Pongolan Periods
    • Neo- Era: Methanian, Siderian Periods
  • Proterozoic Eon
    • Paleo- Era: Oxygenian, Jatulian or Eukaryian, Columbian Periods
    • Meso- Era: Rodinian Period
    • Neo- Era: Cryogenian, Ediacaran Periods

"Jack Hills" in Latin: Colles Jacobei -- the Collijacobean Era?

I've found  Chaotian (geology) for the very earilest Earth, before the Moon's parent body struck it.

In that proposal, it is divided (Neo-) Titanomachean, Hyperitian, (Eo-) Erebrean, Nephelean

The  Titanomachy was the Olympian deities fighting the Titans, an earlier generation of deities.

Erebus - primordial darkness, nephelê - cloud
 
Here's a Paleozoic timeline:
  • 1822: Carboniferous
  • 1835: Cambrian, Carboniferous
  • 1839: Cambrian, Silurian, Carboniferous
  • 1840: Cambrian, Silurian, Devonian, Carboniferous
  • 1841: Cambrian, Silurian, Devonian, Carboniferous, Permian
  • 1879: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian

Here's a Mesozoic timeline:
  • 1822: Cretaceous
  • 1829: Jurassic, Cretaceous
  • 1834: Triassic, Jurassic, Cretaceous

An old name for Ediacaran is Vendian.

I was motivated to create this thread because of a science essay by Isaac Asimov that I'd read long ago. I'm sure that I still have it, but I'd have to search for it.

Geologists Adam Sedgwick and Roderick Murchison were evidently very busy -- they get credit for much of the Paleozoic timeline.
 
This division of geological time is now being formalized with  Global Boundary Stratotype Section and Point with each GSSP marking the beginning of a geological time division. Each one has a type location that exemplifies it.

The most recent one, the Meghalayan Age, is defined using mineral deposits in Mawmluh Cave in Meghalaya, India that record a climate event around 2200 BCE that involved big droughts in the Middle East and nearby.

 List of Global Boundary Stratotype Sections and Points lists all of them, as well as time divisions that do not have any. Each GSSP or candidate spot has some geological markers that define it: magnetic, isotopic, climatic, and/or biological.

They have been defined for nearly all of the Phanerozoic ages. Undefined ones: Cenozoic: 3/24, Cretaceous: 5/12, Jurassic: 3/11, Triassic: 4/7, (Mesozoic: 12/30), Permian: 2/9, Carboniferous: 4/7, Devonian: 0/7, Silurian: 0/8, Ordovician: 0/7, Cambrian: 4/10, (Paleozoic: 10/48) (Phanerozoic: 25/102)

One of the Cambrian epochs is unnamed, and four of its ages are also unnamed.

The Ediacaran was named after the Ediacara Hills at the north of the Flinders Ranges in South Australia. Its GSSP is at Enorama Creek there.

The beginning of the Cryogenian is now defined chronologically, but geologists are looking for a good location for a GSSP, likely the beginning of its ice ages.

It and earlier subdivisions are defined with specific times rather than with geological markers:  Global Standard Stratigraphic Age
 
When you get into local timescales for a given province, things can get kind of fun. Around here, paleontologists have a separate timescale used for dividing up mammal history on the continent (There's a different one for Europe, if you're on the other side of the pond). The Irvingtonian age in that system is named for the little neighborhood adjoining mine here in the Bay Area; I walk past the old excavation site on my morning walks. The Barstovian is named for Barstow, CA, where I used to have family and still visit from time to time when the school geology trip treks out to Rainbow Basin for a mapping exercise. The Rancholabrean takes it's name from the famous La Brea tarp pit site in downtown Los Angeles.
 
Here they are:

Looking at  Global Boundary Stratotype Section and Point the largest number of GSSP's are in Europe, with similar proportions in China, North America, and the rest of the world.

No eon is named after a place, and no era, but of the periods, 3 are named after places in Wales, and 1 each after places in England, Russia, and Australia.

The Late Pleistocene age does not have a typical sort of name for geological ages, though it would likely get one when it gets its GSSP. Likely Tarantian.
 
Going to earlier times, here are the nationalities of the places that the ages were named after:
  • Cenozoic: IN GL GL , IT JP IT IT / IT IT , IT IT IT IT FR FR / DE BE , IT UK FR BE , UK DK DK
  • Cretaceous: NL FR FR FR FR FR , FR FR FR CH CH FR
  • Jurassic (CH): *Ti* UK UK , UK UK FR DE , FR DE FR FR
  • Triassic: CH AT AT , IT AT , RU PK
  • Permian (RU): (CN) CN CN , (US) US US US , (RU) RU RU RU KZ
  • Carboniferous: <US> RU RU , RU , RU , <US> RU , BE , BE
  • Devonian (UK): BE BE , FR DE , DE CZ CZ
  • Silurian (UK): (CZ) CZ , (UK) UK UK , (UK) UK UK , (UK) UK UK UK
  • Ordovician (UK): UK US SE , AU CN , SE UK
  • Cambrian (UK): (CN) -- CN CN , (CN) CN US CN , (--) -- -- , (CA) -- CA
() means epoch and <> means subperiod. Uses Tarantian for Upper Pleistocene.

*Ti* - in Greek mythology, Tithonus was the son of Laomedon of Troy, and he fell in love with Eos, the Greek goddess of dawn.

IN = India, GL = Greenland, IT = Italy, JP = Japan, FR = France, DE = Germany (Deutschland), BE = Belgium, UK = United Kingdom, DK = Denmark, NL = Netherlands, CH = Switzerland (Confédération Helvétique - Helvetic Confederation), AT = Austria, RU = Russia, PK = Pakistan, CN = China, US = United States, KZ = Kazakhstan, CZ = Czechia, SE = Sweden, AU = Australia, CA = Canada

Country Codes List - ISO ALPHA-2, ISO ALPHA-3 and Numerical Country Codes - Nations Online Project has a full list.
 
I'lll take those proposed Precambrian divisions, reverse their directions, and give nationalities of places in them:
  • Proterozoic Eon
    • Neo- Era: Ediacaran AU, Cryogenian Periods
    • Meso- Era: Rodinian Period
    • Paleo- Era: Columbian (US), Jatulian or Eukaryian, Oxygenian Periods
  • Archean Eon
    • Neo- Era: Siderian, Methanian Periods
    • Meso- Era: Pongolan ZA+SZ, Vaalbaran ZA+AU, Periods
    • Paleo- Era: Isuan GL, Acastan CA, Periods
  • Hadeon Eon: Jack Hillsian AU or Zirconian, Chaotian Eras
ZA = South Africa, SZ = Swaziland

The Rodinian and Columbian are named after supercontinents Rodinia and Columbia, with Rodinia's name coming from Russian rodina "motherland, birthplace", and Columbia's name coming from the Columbia Plateau in the western US.
 
in the modern era, the International Commission on Stratigraphy is the closest thing you have to an "official" body for accepting new definitions of the global geochronology. I understand they are set to vote on the controversial definition of an Anthropocene Epoch later this year, unless pandemic restrictions impede their convention. The working group they assigned to the issue has provisionally approved the designation, so it seems likely the larger group will as well. It is quite a common topic of discussion with my extended family when we all get together, as it is an uncommon blend of the academic fields we are variously engaged in (two geologists, an anthropologist, a sociologist, and a whole bunch of teachers walk into a bar...).

If we really wanted to start a ruckus on this forum, we could bring up the very controversial work "A Billion Black Anthropocenes or None", a social philosophy treatise that can best be described as geology seen through the lens of critical race theory...
 
 Anthropocene - seems like an issue that I'd prefer to avoid. A good part of it is how to mark out its beginning.

For nearly all of our species' history, our ancestors lived much like their predecessor species, hunting and gathering, or more collectively, foraging.

But a big change happened in the Holocene, when we invented agriculture in several places, independently of each other.

The first farmers lived in the Middle Eastern Fertile Crescent at the beginning of the Holocene.  Neolithic Revolution

In eastern Asia, the two primary centers of crop-plant domestication were the lower Yellow River (northern) and the lower Yangtze River (southern).

In Africa, the three primary centers of domestication were the Ethiopian highlands, the Sahel and West Africa.

Primary centers of domestication elsewhere were New Guinea, Central America, and parts of South America.

I'm saying "primary" because some places qualify as secondary ones, where more crop plants were domesticated by people who already had some.
 
 List of largest cities throughout history has the largest cities over time. However, its upper limit of 10,000 for the early Ukrainian ones is contrary to  Settlements of the Cucuteni–Trypillia culture which states that they were much larger, like Maidanets at 30,000. The other two mentioned, Dobrovody and Talianki, were around 20,000. All for around 3,500 BCE.

A millennium or so later, those big cities faded and Egyptian and Mesopotamian cities started growing impressively large. 50K - 100K in Mesopotamia, 30K in Egypt, and 40K in the Indus Valley, now Pakistan. By 1000 BCE, Egypt, Mesopotamia, and China had cities as large as 100K.

By 1 CE, Rome has 1 million people, and by 1000 CE, the champions were Baghdad and some Chinese cities at around 1M people.

The first European champion city was London in the 19th cy. at 1 - 2 M people, the NYC beat London in the early 20th cy. with 8 M people, and then Tokyo beat NYC in 1965 with 15 M people.

-

Returning to technology, for copper use, 5000 BCE, for bronze use, 3300 BCE, and for iron use, 1200 BCE.

But even then, agriculture-using societies were mostly agrarian for a long time, dominated by agriculture. But that changed in the Industrial Revolution, and an important part of it was the development of steam engines. Looking at them, the first one that was practical for industrial use was the  Watt steam engine in 1776.  Industrial Revolution identifies 1765 to 1820 in Europe and 1840 in the US. Part of it was the exploitation of coal for fuel, something that ended the First Age of Renewable Energy, something that encompassed all the history of humanity before then. So we might use 1776 as the date of the start of the Anthropocene.

The  Second Industrial Revolution was roughly from 1870 to 1914.
Advancements in manufacturing and production technology enabled the widespread adoption of technological systems such as telegraph and railroad networks, gas and water supply, and sewage systems, which had earlier been concentrated to a few select cities. The enormous expansion of rail and telegraph lines after 1870 allowed unprecedented movement of people and ideas, which culminated in a new wave of globalization. In the same time period, new technological systems were introduced, most significantly electrical power and telephones. The Second Industrial Revolution continued into the 20th century with early factory electrification and the production line, and ended at the beginning of World War I.

...
The Second Industrial Revolution was a period of rapid industrial development, primarily in the United Kingdom, Germany and the United States, but also in France, the Low Countries, Italy and Japan. It followed on from the First Industrial Revolution that began in Britain in the late 18th century that then spread throughout Western Europe. While the First Revolution was driven by limited use of steam engines, interchangeable parts and mass production, and was largely water-powered (especially in the United States), the Second was characterized by the build-out of railroads, large-scale iron and steel production, widespread use of machinery in manufacturing, greatly increased use of steam power, widespread use of the telegraph, use of petroleum and the beginning of electrification. It also was the period during which modern organizational methods for operating large scale businesses over vast areas came into use.

...
Landes (2003) stresses the importance of new technologies, especially, the internal combustion engine, petroleum, new materials and substances, including alloys and chemicals, electricity and communication technologies (such as the telegraph, telephone and radio).
Click to expand...
Animal transport likely dates back to the domestication of large animals like bovines and donkeys and horses. They would first be used as beasts of burden, then used to pull carts and wagons. The first engine-driven vehicles were rail vehicles, and the first use of them in railroads was the Manchester - Liverpool Line in 1830. Railroads were developed rapidly in Britain, leading to the  Railway Mania in the 1840's -- railroads were the dotcom companies of the day. Efforts to develop flat-road "steam cars" were not very successful, however, and the first successful engine-driven flat-road vehicle was Carl Benz's Patent-Motorwagen ("Patent Motorcar"). Like most later flat-road cars, it used a gasoline internal-combustion piston engine. The first successful diesel engine was introduced in 1898, and diesel engines gradually displaced steam engines in land and water transport.

Water vehicles may be as old as humanity, but they were small boats for a long time. They were first powered by their users, using oars to row them, but some millennia ago in various places, some people invented sails, capturing wind energy to propel their boats. Thus, sailboats and sailing ships and rower-sailers like triremes and galleys. That changed in 1807, with Robert Fulton's first successful engine-driven ship.

The first engine-driven ship to routinely do transoceanic voyages was the SS Royal William, starting in 1831. However, it was a motor-sailer, having sails along with its steam engine. It was only late in the 19th cy. that engine-driven ships were built without sails, and they soon were built in impressive sizes, much larger than even the largest sailing ships.  Timeline of largest passenger ships  List of large sailing vessels
 
The Third Industrial Revolution is the  Digital Revolution and it is ongoing.

All that was rather far afield, and I think that it shows the difficulty of pointing to some sharply-defined event as the beginning of the Anthropocene. Humanity's ecological impacts have been growing since the invention of agriculture, and growing without sharp dividing lines.

So if I had my say, I would *not* define an official Anthropocene.
 
On the other hand, Epochs aren't usually defined by a sharp, single event. Geological changes don't happen quickly in human terms, even when they are rapid events to a geologist, nor do most events affect the world strictly uniformly. The definition of periods, epochs, eras and so forth is more a shorthand for noticing common characteristics in the deposits from a period of time. It was always the habit of archaeologists to define shorthand anthropogenic "layers" "levels" or "archaeostrata", even though such strata likewise usually have diffuse edges and dating that varies by site.

That said, I'm concerned that ethnocentrism may be an influential source for any date they set, and you're correct to indicate why. "Science has no country, but a scientist has a country..."[1]. One of my students who recently graduated is now pursuing a dissertation study on the way geological periods and and other terminology are used in various industry-building projects in the global South, and she is not alone these days in wondering about the uncomfortable frontiers between geology and socioeconomic or political processes.
 
lpetrich said:
The Third Industrial Revolution is the  Digital Revolution and it is ongoing.

All that was rather far afield, and I think that it shows the difficulty of pointing to some sharply-defined event as the beginning of the Anthropocene. Humanity's ecological impacts have been growing since the invention of agriculture, and growing without sharp dividing lines.

So if I had my say, I would *not* define an official Anthropocene.
Click to expand...

Fourth:

The four industrial revolutions are coal, gas, electronics and nuclear, and the internet and renewable energy. Beginning from 1765 through the present day, we've seen an amazing evolution.
Click to expand...
 
Politesse said:
When you get into local timescales for a given province, things can get kind of fun. Around here, paleontologists have a separate timescale used for dividing up mammal history on the continent (There's a different one for Europe, if you're on the other side of the pond). The Irvingtonian age in that system is named for the little neighborhood adjoining mine here in the Bay Area; I walk past the old excavation site on my morning walks. The Barstovian is named for Barstow, CA, where I used to have family and still visit from time to time when the school geology trip treks out to Rainbow Basin for a mapping exercise. The Rancholabrean takes it's name from the famous La Brea tarp pit site in downtown Los Angeles.
Click to expand...

There are different names for the glacial maxima and interglacials in Southern Germany (based on how far North the Alps' glaciers reached) from the ones used in Northern Germany (based on how far inland the Scandinavian Ice Shield reached).
 
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